Safety valve



Sept. l1, J. ..MCKEAGUE 2,567,439

- SAFETY VALVE Filed Jan. 18, 1947 2 sheets-shea 1l f M my l m y 57i; .57 j; 79 50 76?? i 43 74?, M7257- l 72 l) Sept. 11, 1951` J. J. MoKl-:AGUE 2,567,439

SAFETY VALVE Filed Jan. 18, 194'? 2 Sheets-Sheet 2 IIIII -i QW .JZ 5 f4 40 Y 5f 50 4g 54 i@ 7 49 y Il f 55 46 H 47 l VI i, I f I 9 f f o 1 70 65 I 58. l' 64 /zyzz for.' g/fizes IM-f-'e ue a .mW/7656 Patented Sept. 11, 1951 UNITE-D STATE-S PATENT OFFICE SAFETY VALVE James'J. McKeague; Chicago, lll. l

Application January 18, 1947,1SerialNo. 722,773v

22 Claims.

e 1 This invention relates to` a safety valve which is especially adapted for use in conjunction with and upon gas and vapor pressure.l lines and sys'- tems including refrigeration lines and systems, gas and vapor lines and systemsn employed in the petroleum industry, and elsewhere'.

- More particularly, the presentinvention relates to a safety valve which mayA embodyv a rupturable member on the outlet side thereof.

It has not been practical heretofore' to employ a rupturable safety member on the outlet side of prior safety valves. This has been' due largely to the fact that if gas or vapor under pressure leaks int'o the body or interior of such prior safety valves it tends to accumulate and to build' up pressure therein and thus to lock the movable valve member iii closed position upon' its seat and against' opening or to raise the pressure'release point of the movable valve member to a danger point, dependingupon the pressure built upin th'ebody of the valve andtheeiectiveA sur'- face area on the inner side of the movablevalve member and on which the accumulatedA gasor vapor pressure in' the body or main chamber vofv thel valve isv exerted` Thus, for example, a'ssuming that the movable valve member in"v such a prior safety valve were set to release at' a pressure of 200poundsper square inch and thatthe spring embodied in the said safety valvemem-ber is set accordingly to yield at this pressureY and thus allow the movable valve member to' open', thatis, to be raisedf off? its? seat. Assuming further that gas or vapor should leakA past the movable valve member until a pressure ofn 25 pounds per square inch` has accumulated or' has been built up in the body or main chamber of the saidsafetyvalve member and that the total surfacefarea of the back or inner side of the movable valve member is one square inch'. Such' anac'- cumulated pressure of 25 pounds per square in'c'h in thev body or main chamber of the saidf safety valve member wouldtherr be effec'tiveltoA increase the release point of the movable valve member significantly beyond its normal release pressure point of 200 pounds per square inch or, in other words, to a pressure releaser point consisting of .thef normal yielding pressure of they spring (200 pounds per square inch) and the accumulated pressure ofthe gasfor vapor' inthe main chamber or body of the safety valve member. Thus a dangerous conditioniwould be built-fup-inizthef gas or vapor line or system with which such asafety valve might beI associated.

Refrigerant gases are extremely diicult't'o retainiand most priorsafety valves leakandseep, which results` in* costlylossesV of valuable gases.

Moreover, repair and service men often when finding a leaking valve, cap or plug the outlet to retain the refrigerant in the system until such time as replacement can be made. During this period the vessel or system has no protection from over-pressure and many serious accidents have taken place. v

Also,r snow and water and foreign matter tend to enter the housings of such conventional prior safety valves through the' outlet and vent openings thereof and, in so doing, tend to rustv the coil springs and other ferrous metal parts embodied therein, thereby rendering such prior safety valves unreliable in their operation and as to their pressure yielding point, and necessitating frequent repair and replacement of the ferrous metal working parts embodiedtherein.

In order to overcome the foregoing difficulties and unsafe conditions experienced in the use of prior safety valves of the character referred to above, some manufacturers of refrigeration equipment place the rupture member between the safety valve and the gasor vapor pressure line or system with which it is associatedV so` that if and when the' rupturable safety member bursts the safety valve comes into operation. However, this arrangement is objectionable for the reason that inforder to replace the rupturable member all of the gas or vapor must be removed from-the gas or vapor pressure line or vessel with which the rupturable member is associatedand this frequently results in the lossf of substantial quantities of relatively Vexpensive gases or vapors such, for example, asvthose whichare used in refrigerat-ion systems.

In an'endeavor to overcome the foregoing and other diiculties experienced in the use of prior safety valves, valve manufacturers of certain safety valves attach'the movable valve member toanexpansible bellows member (sometimes referred to as al Sylphon), whichis arranged in the body or main chamber of the valve housing.

In the aforesaid prior safety valves embodying an expansible bellows member, a housing or cap is employedfor retaining the expansible bellows member inrplace and for the support of the spring which supplies the required tension and the outlet of the valve is-Yprvided with va frangible or rupturable disc. If thistype of valve develops a leak and gas or vapor will seep past the contact between the-movable'valve member and its seat and,as a result, a gas or vapor pressure will build up inthe body of the'valve. This pressure tends to contractthe expansible bellows member against'the tension of the spring and'thus tends tofopen thevalve. However, should gas or vapor :atea-fac leak or seep through the expansible bellows member, due to cracks, pin holes, imperfect soldering, etc., and accumulate in the housing enclosing the expansible bellows member and spring, this pressure will neutralize the action of the expansible bellows member and a locking action will take place, similar to that which takes place in conventional safety valves.

To overcome the danger of this possible locking action, manufacturers of this type of valve provide a vent port or small hole in the expansible bellows member and spring housing to allow for the escape of any gas or vapor which may leak or seep through the expansible bellows member. Such prior safety valves embodying an expansible bellows member work, in general, quite satisfactorily as long as the atmospheric vent port or opening formed in the spring housing is open and free to perform its intended function of allowing any gases or vapor which may leak through the expansible bellows member to be relieved by escapement to the atmosphere through the said vent port or opening. However, it quite frequently happens in the use of such prior safety valves that the said vent opening or port therein will become plugged with accumulated foreign matter and nullify the purpose for which it was provide.

Also, the expansible bellows members embodied in such prior safety valves are expensive and, as a result, there are relatively few of such safety valves in use and their use has been confined will remain open or in unseated position until the pressure in the line or vessel has been reduced to the point at which the movable valve member will be automatically closed or reseated, whereupon the rupturable member may be readily replaced, once it has been ruptured, without removing the new safety valve from the gas or vapor pressure line or vessel with which it is associated, and without removing the gas or vapor from the pressure line, vessel, or system with which the new safety valve may be associated.

primarily to relatively large gas and vapor pressure systems.

Accordingly, a primary object of the present invention is to provide a new and improved and relatively simple safety valve which may embody a rupturable member on the outlet side thereof, and for use in gas and vapor pressure lines, vessels and systems, and which in use is free from and overcomes and eliminates the foregoing and other objectionable features of the prior safety valves to which reference has been made above.

Another object of the present invention is to provide a new and improved safety valve which may embody a rupturable member on the outlet side thereof for use in gas and vapor pressure lines and systems, and which does not embody either a coil spring or an expansible bellows member for controlling the pressure release point and operation of the movable valve member, such as have been embodied in prior safety valves and with the consequent disadvantages referred to above, and in which the pressure release point and operation of the movable valve member are under the sole control of a flexible diaphragm embodied in the new safety valve.

A further object of the present invention is to provide a new and improved safety valve which may embody a rupturable member on the outlet side thereof for. use in gas and vapor preslsure lines and vessels and in which any gas or vapor pressure which may build up or accumulate in the body or main chamber of the new safety f' valve will tend to open or unseat the movable valve member rather than tending to close or seat the movable valve as in certain of the comparable prior safety valves which have been referred to above.

Still another object of the present invention is to provide a new and improved and relatively simple safety valve which may embody a rupturavble member on the outlet side thereof, and for use in gas or vapor pressure lines or vessels, and

in the use of which the movable valve member A further object of the present invention is to provide a new and improved and relatively simple safety valve in which the movable valve member, after having been unseated, may be readily reseated in case of'leakage or seepage between the movable valve member and its seat by merely tapping the flexible wall of the valve housing with a light tool, such as the handle of a screwdriver, and without disassembling the safety valve member as has been necessary in the use of certain of the prior safety valve members. embodying an expansible bellows member.

Still further objects of the present invention are: to provide a new and improved and relatively simple and inexpensive safety valve which does not require a special cover or cap as is required in safety valves embodying an expansible bellows member; which is free from any vent port or opening for the entrance of snow, water and other foreign matter and which is otherwise so constructed that water, snow and other foreign matter cannot enter into the body of the new safety valve to interfere with the opera.- tion thereof; which is so constructed that once it has been assembled and adjusted and the new safety valve applied in position of use interference with its properly adjusted working parts is prevented; which may be readily clamped in position of use upon a pressure line or vessel without damaging or distorting or otherwise interfering with the flexible diaphragm embodied in the new safety valve; and which is so constructed and arranged that the flexible diaphragm cap member embodied therein has a gas or vapor tight threaded sealing engagement with a portion of the main valve housing in which it is mounted so that the use of a sealing gasket at this point is eliminated. Y

Other and further objects of the present invention will be apparent from the following description and claims and are illustrated in the accompanying drawings which, by way of illustration, show preferred embodiments of the present invention and the principles thereof and what I now consider to be the best mode in which I have contemplated applying these principles. Other embodiments of the invention embodying the same or equivalent principles may be used and structural changes may be made as desired by those skilled in the art without departing from the present invention and the purview of the appended claims.

In the drawings:

Fig. 1 is a top plan view illustrating a preferred embodiment of the new safety valve;

Fig. 2 is a central vertical sectional view on line 2-2 in Fig. l;

Fig. 3 is an elevational view of the combination movable valve member, guide unit and adjustment barrel therefor which are embodied in the new safety valve;

Fig. 4 is a top plan view on line 4-4 in Fig. 3 showing the combination movable valve member,

ygliiid'e unit andE adjustment barrel therefor shown inv Fig. 3;

Fig. z ,isa sectional plan view on lines 5-5 in* Fig: 2;

6 isa fragmentary central vertical sectional view illustrating a modified form of a flexible diaphragm. cap which may be embodied 'in the nw safety valve;

Fig; 71 is a fragmentary central vertical sectional-viewv illustrating anotherl modification of a flexible diaphragm cap which may be embodied 'in-the new safety valve;

Fig. 8 is a fragmentary central vertical sectional view illustrating a further modified form of a flexible diaphragm cap which may be embodied inthe new safety valve;

Fig. 9- isa fragmentary central. vertical sectional view' illustrating still another modified form of the new safety valve; Fig. l0 is a fragmentary top plan view illustrating an additional modification of a flexible diaphragm capand auxiliary resilient tensioning membertherefor which may be embodied in the new safety valve; and y Fig. 1l is-a central vertical sectional' view on line I'I-I'I in Fig. 110.

A safety-valve embodying-a typical form of the present invention is illustrated in Figs. l to 5, inclusive, of the drawings whereinit is generally indicated at IU, and comprises a valve housing `'or body I'I which may be made of brass or other 'suitable metal. The valve housing II includes a main internal chamber I2 having an externally threaded inlet nipple I3' and an internally 4threaded outlet nipple I4. The bottom wall of 'the internal chamber I2 ofthe valve-housing II is' formed by a substantiallyconical-shaped valve seat I5 in the inner surface of which an annular 'groove' I6 is provided; A movable valve member I1tA is normally seatedY upon the-valve seatV I5 so as to close the inlet' passage I8 from the inlet nipple I3 into the interior or main internal -chamber'l2i of the valve housing II. To this end the movable valve member IlA includes a valve stem I9 whichV has a base or head 20 formed, thereon at the lower end thereof and this head has'a depending annular flange or skirt 2|v formedintegral therewith, as shown in '-Figs. 2 and 3. flexible sealing gasket 22, which ymay be made of any suitable material such, for

example,l as synthetic resinous materials inlcludingk Saran Resistoex Neoprene or othersuitablev materials, is attached to the head 2,0 of theA valve member I'I and its depending annular skirt 2Ik on the inner side of thelatter, as shown in Figs. 3 and 4. The annular flange Dertien. of the sealing gasket 22` normally bears upon. the valve seat I5Y to provide a secondary seal andthe body or main extent of the sealingl gasket 22 normally bears upon the valve seat., I5 about the inlet I8 to provide the primary seal between these parts., This arrangement provides an area or compartment 23 betweenY the stationary valve. seat I5 and the flexible seallngk gasket- 22 (Fig. 2) when the movable valve lmember and the sealing gasket 22 carried thereby are in closed position, as in Fig. 2.

The valve stem I9 is externally threaded and has .a substantially cylindrical manuallyV operable adjustment barrel or member 24 mounted thereon. This manually operable adjustment barrel or member. 24 is provided with aA centrally arranged 'and` threaded opening 25.for the reception of the externally threaded. valve stem I9 (Fig. 2). A

" substantially 'square' combination lock washer and 6. guidemember 2li-is mounted on the threaded stein- ISI of the movable valve member' |21. and to this end the combination lock washer'andgui'demenrber 25 is provided with. a centrally arranged threaded opening 2'!v for the reception. of the threaded' stem I9 of the valvemember: I:'I:.. The substantiallyy squarecombinationlock washer' and guide member-26 (Fig. e) is=slidab1ymounted-1in the internal cylindrical cavity 28e of a substantially cylindrical flexible diaphragmL cap mem.- 'ber 29A which may be made of a suitable. synthetic resinousl plastic material, or other. suitable material which will be described; hereinafter.- The side wallof thisexible diaphragmeap member 2Sy is` externally threaded, as.. at 3D,and is` removably and tightly or closely threaded into an internally threaded portion. 3-I. of. the.- body off-the valve housing II. `The flexible: diaphragm cap member 29- hasv an enlarged'. and substantial.- ly'annular clamping flange 32 .which` normally bears upon the upper edge 33' of the` internal chamber |12 in the valve housing II (Fig. 2)-,

The flexible diaphragm. cap. member 29, which is embodied in the new safety valve I Ilmay; be made of any suitable-synthetic resinous.: thermo.- plastic material such, for example, as vinylidene chloride copolymer (Saran-Dow.f Chemical 0o.), or, but less desirrfibly,v of metalY of.. suitable by grooves 36 alternated with correspondingraised annular concentric ribs 31. The inner.- most corrugation or annular groove 36 bears down at its underside upon the convexly rounded upper end portion or surface 44 of the substantially cylindrical manually operable adjustment barrel member 24 which is vmounted on the valve stem I9-, as shown in Fig. 2. Y

The outlet nipple I4 of the valve body II is internallyl threaded, as at 38 (Fig. 2) and the externally threaded shank 39 of a safety member in the form of a plug 40 is removably thread'- ed into the internally threaded outlet nipple I4. The safety member or plug 40 has an enlarged clamping ange or shoulder 4I which is disposed externally of the outer end of the outlet nipple I4 and the safety member or plug 49 has an internal cavity or chamber 42 which communicates by way of the outlet nipple I4 with the main chamber or cavity I2 in the valve body II. The outer end of thel safety member or plug 40 is closed by an elastic flexible diaphragm 43 which is formed as an integral p-art of the safety member or plug 43, as shown in Fig. 2.

The plastic resinous flexible diaphragm cap member 29 is tightly threaded into the portion 3| of the metal body of lthe valve housing I I and this tight plastic-to-metal sealing engagement of these parts provides a gas and vapor tight seal and eliminates the necessity for a, sealing gasket at this point.

The use and operation of the form of the new safety valve shown in Figs. 1 to 5, inclusive, of thefdrawings are as follows: The new safety valve f l"Ill may be attached by its externally threaded inlet nipple I3 to a gas or vapor pressure line, system, or vessel, whereupon gas or vapor under pressure will enter the valve inlet I8. However, the valve head 20-22 is normally seated upon the valve seat l5 by reason of the fact that the elastic flexible diaphragm 34 presses downwardly upon the rounded upper surface 44 of the manually operable adjustment barrel member 24 with suflicient force to maintain the valve head 20-22 upon its seat I5 and thus prevent gas or vapor under pressure from entering the valve body II by way of the valve inlet I8.

It will be not-ed, in this connection, that the manually operable adjustment barrel member 24 may be manually adjusted upon and axially of the threaded valve stem I9, and relative to the elastic flexible diaphragm 34, so as to vary the tension upon and the effective downward pressure of the elastic flexible diaphragm 34 upon the manually operable adjustment barrel member 24 and the valve I9-I'I-20-22 upon which lthe said manually operable adjustment barrel member 24 is mounted and so as to vary correspondingly the gas or vapor pressure release point at which the valve head I'I--20-'22 will be raised off its seat I5. The combination lock washer and guide member 25 may likewise be manually adjusted upon and axially of the threaded valve stem I9 so that it is at all times disposed immediately below and in contact with the bottom surface of the manually operable adjustment barrel member 24. Hence the member 26 functions both as a guide member and as a lock nut to retain the manually operable adjustment member 24 in a preselected adjusted position on the valve stem I9 and against accidental displacement therefrom.

If and when the pressure of the gas or vapor entering the valve body II by way of the inlet nipple I3 and inlet passage I8 becomes greater than the effective pressure exerted by the elastic flexible diaphragm 34 upon the valve head II-20-22, by way of the manually operable adjustment member 24 and the valve stem I9, gasvor vapor from the line or vessel with which the new safety valve is associated will enter the valve body II by way of the inlet nipple I3 and inlet passage I8 and will thereupon act upon the bottom surface of the valve body 2li-22 to raise the valve head I1-20-22 off its seat I5, thereby first breaking the primary seal between the sealing gasket 22 and that portion of the stationary valve seat I5 which defines the marginal edge of the inlet I8. As the primary seal between the sealing gasket 22 and the valve seat I5 is thus broken the incoming gas or vapor enters the auxiliary chamber 23 and thus affects and acts upon a relatively much larger surface area of the valve head 20-22 than is exposed to the pressure of the incoming gas or vapor at the primary seal between the perimeter or marginal edge of the inlet I8 and the valve seat I5. This results in a corresponding increase in the total effective force applied upon the Valve head 20-22 of the movable valve 4member I1 to overcome the flexing action of the flexible diaphragm 34 and hence the movable valve member I1 is unseated with a quick, snaplike action. The valve stem I9 and the guide member 26 and the manually adjustable pressure control member 24 will thus be raised upwardly and the rounded upper surface 44 of the manually operable adjustment barrel member 24 will bear against the inner surface of the elastic flexible diaphragm 34 and thus exert an upwardly flexing action thereon. During this movement of the valve member I1-2 0-2 2 I 9 and of the manually operable adjustment barrel member 24 carried thereby the valve member I1-20-22--I9 is guided within the interior 28 of the flexible diaphragm cap member 29 by the combination lock washer and guide member 26 (Figs. 2, 3 and 4) which, as shown in Fig. 4, is substantially square in design so that it has a sliding flt with the inner surface of the flexible diaphragm cap member 29, but, due to its substantially square shape (Fig. 4) has limited frictional engagement therewith.

When gas or vapor pressure in the body of the new safety valve overcomes the tension of the elastic flexible diaphragm 34 on the adjustment barrel 24 the movable valve member I1 will either assume a floating position in the valve housing or will rest upon the valve seat I5 under its own weight and the force of gravity acting thereon.

The annular groove I6 in the valve seat I5 serves to receive any foreign particles or matter which might otherwise accumulate on the upper surface of the valve seat I5 and interfere with either the primary or secondary seal between the parts I5 and 22.

As the valve head I'I--20-22 is thus raised oil' its seat I5 the gas or vapor will flow into the interior or main chamber I2 of the valve body II and thence into the outlet nipple I4 and the interior 42 of the rupturable safety member 40 attached thereto whereupon it will press against the inner surface of the elastic flexible rupturable wall 43. The safety member 40 may be of any suitable type but for this purpose I have found that the construction disclosed in my earlier United States Patent No. 2,370,870 issued March 6, 1945 on a Safety Device is well suited. However, the present invention is not limited to the use of any of the safety members disclosed and claimed in my aforesaid earlier Patent No. 2,370,870, since other safety members or frangible discs may be used with the safety valve of the present invention.

The elastic flexible rupturable wall 43 may be constructed so that it will rupture at a preselected pressure so that it will yield and flex under normal and safe operating pressures in the valve body II but if and when a dangerous pressure condition develops within the valve body II and in the interior 42 of the safety member 40 the same will rupture the elastic flexible wall 43 of the safety member 40 and thereby relieve the dangerous or unsafe condition referredto. As pointed out in my aforesaid earlier Patent No. 2,370,870 the elastic flexible rupturable wall 43 may be made of a suitable synthetic thermoplastic resin for which I have found vinylidene chloride copolymer (Saran-Dow Chemical Co.) to be admirably suited although other synthetic resinous materials, and even metals, may be employed in making both the flexible diaphragm cap member 29 and its elastic flexible wall 34 and the safety member or plug 40 and its elastic flexible rupturable wall 43.

After the elastic flexible rupturable wall 43 is thus ruptured to relieve a dangerous or unsafe pressure condition in the vessel so protected, the elastic flexible diaphragm 34 embodied in the elastic flexible diaphragm cap 29 will then act upon the manually operable adjustment barrel member 24 and its upper rounded surface 44 and through the valve stem I9 to reseat the movable valve head I'I--20-22 upon its Seat I5, with a relatively fast or quick and snap-like action, and thus prevent further loss of gas or vapor from the pressure line, vessel or system which the new safety valve is associated. If a dangerous or overpressure condition still exists in the gas or vapor pressure line or system, .re1- ative to the pressure release point of the new safety valve, the movable valve member I'I will beraised off its seat I5, thereby relieving the excess pressure until a pressure condition is reached at which the movable valve member I'I will reseat upon its seat I5. The new safety valve will then function as a-n ordinary safety valve until the ruptured safety member or plug 40 may be unscrewed from within the internally threaded outlet nipple I4 .and replaced by a new rupturable safety member 40.

If the movable valve member |'I-20-22 should for -any reason fail to reseat i-tself tightly upon its seat I5, due to the presence of foreign particles or dirt on the seat I5., :the upperv surface of the elastic Vflexible diaphragm V34 or the side wall flange 3.2 of the `elastic flexible diaphragm cap 29 may be tapped lightly with a suitable small instrument, such as the handle of a screwdriver, so as to rmly reseat the movable valve member I .'I-210--22 upon its seat I5, whereupon the yelastic flexible diaphragm 34 will function to hold the movable valve member -I 1--20-22 firmly upon its ,seat I5.

Y The combination lock washer and lguide member 2.5 and the substantially conical shape of the valve seat rI5 'assure that the movable valve f member I 1 20-22 will at all times be properly reseated upon the valve seat I5 so as to close the mouth of the inlet passage I8 therethrough at `the primary seal between the sealing gasket 22 on the valve 'head 20 and the marginal edge ofthe inlet opening I8 through the valve seat -I 5.

It will be noted that the elastic flexible dia- .phragm .'34 serves the function of and replaces the conventional coil spring embodied in the prior safety valves of a' comparable lcharacter or type, and that which the rupturable safety member 01'v plug 40 is arranged on theoutlet side of the new safety valve the difficulties referred to hereinbefore Yand which have heretofore lbeen experienced in the use of prior safety valves are overcome .and substantially eliminated. Moreover, .once the manually .operable `adjustment barrel 124 has been properly adjusted to the desired pressure and working conditions and the new safety valve I0 -is sealed by a suitable seal (not shown) the internal parts thereof cannot be tampered with .or read'justed until the seal is broken.

It will also 'be-noted that if in the use of vthe new safety valve shown in Figs. l to 5, inclusive, gas or vapor should seep past the point of contact -or primary seal between the movable valve member IT`2022 and its seat I5 and accumulate in the interior I2 of the valve body I'I such gas or vapor will exert substantially the same and an equal pressure vupon both the undersurface of the elastic flexible diaphragm 34 and upon the upper or inner surface of the movable valve member I 'I-20--22. The two opposing forces thus developed, one tendingto unseat the movable valve member Il-20-22 and the other tending to seat the same, will counterbalance or offset each -other and no danjgerous condition will thus be developed with-in the interior i2 of the valve body II which might cause `the movable valve member Ifi--Z-ZZ to remain xedly closed or seated againstthe pres,- sure of the gas or vapor in the inlet nipple I3 and its inlet passage I8. 'One of the v.hazards experienced in the use of comparable safety 1.0 valves employing a lcoil springv and embodying a rupturable disc arranged on theoutlet .side thereof is thuseliminated in the use of the new safety valve Hlgshown in Figs. l to 5, inclusive, of the drawings.

Moreover, the new safety valve embodying the construction thus described, and as shown in Figs. 1 to 5, inclusive, of the drawings, does not embody any cap orvother enclosure arranged over the flexible elastic diaphragm corresponding to the caps arranged over the valve-reseating coil lsprings Vand expansible bellows members in the prior .safety valves of a comparable character and in which caps or enclosures it has `been customaryto provide an escape vent or port to the atmosphere in case .of .a leak in lthe expansible .bellows member with -the consequent likelihood -of 'building up an opposing or locking pressure conditionrwitb-in the expansible bellows member if and when the aforesaid vent vopening or vport should become clogged or filled with accumulated foreign matter.

In the construction of the new safety valve I0 4which is illustrated in Figs. l to 5, inclusive, of the drawings, the flexibility of the Aelastic flexible diaphragm 34 is materially increased ,by the concentric annular grooves 36 and ribs 31 formed therein, thereby materially increasing the effective travel distance for v:permissible movement cf the movable valve member I-'I-20-22- iii `'in the valve body .i I.

The -ratio of the surface area of lthe 'elast-ic flexible diaphragm 34 to the surface area of that portion yof the valve head II-20-22 which is normally disposed across and closing vthe inlet passage I8 is preferably 'in the lorder of from '7 to $10, inclusive, to 1. This -ratio and the lwall thickness of the elastic flexible diaphragm .34 are vpreferably increased as the vrelease point pressure ofthe vsafety valve 10 is increased. Thus, for example, fora 1A" valve having asurface area of 0.049 sq. in. at and in Vcontact with the inlet passage L8 the internal diameter of the elastic flexible diaphragm 54 should be approximately 3A and the thickness of the elastic .-flexible :diaphragm 34 should be approximately 5%" or v0.093" for a release pressure of 200 lbs. per square inch, when the elastic `flexible diaphragm cap 2-9 and the elastic flexible ydia1t hra-gm -34 which is formed as an integral part thereof are formed of vinylidene chloride copolymer (-Saran-Dow Chemical Co.). Y

The side wall-of the elastic flexible diaphragm cap 2-9 and the clamping flange 3.2 thereon are substantially thicker than the .elastic flexible diaphragm -34 so -that the `elastic -fle-xible -diaphragm 34 is ynot weakened ordistorted when a tool is placed about Ithe -lange 32 to insert .the flexible diaphragm `cap member .34 into .or to remove the same from the valve body II.

A modification of .the flexible diaphragm .cap member -of the present invention is illustrated in Fig. 6 of vthe drawings wherein a portion of a valve body, comparable to the valve body II, is generally indicated at n45. This portion of the valve body is adapted to house a combination lock washer and valve .guide '26 and valve assembly I'I associated therewith, such as are .shown invFig. 4. In this modification of the invention the portion 45 -of lthe -valve vbody has an externally threaded necl; 46 onto which an internally threaded clamping separate ring 41 is detachably threaded. This clamping ring `4'I has `an inwardly extending annular clamping flange 48 at the top :thereof and this clamping flange .48

1l is adapted to have clamping engagement with a substantially annular marginal side wall 49 which is formed integrally with an elastic flexible diaphragm cap member 50. The elastic flexible diaphragm cap member 50 is provided with concentric annular grooves 5| and ribs 52 and is otherwise comparable to the elastic flexible diaphragm cap member 34 which is embodied in the form of the invention shown in Figs. 1 to 5, inclusive, and may be made of the same material.

The modified form of the new flexible diaphragm cap shown in Fig. 6 is somewhat less expensive in construction than, and dilfers from, the elastic flexible diaphragm cap 29 embodied lin the form of the invention illustrated in Figs. ,l to 5, inclusive, in being formed as a separate unit and by being removably clamped in position of use upon the portion 45 of the valve body by means of the separate clamping ring 41 and its clamping flange 49.

A further modification of the elastic flexible diaphragm cap member of the present invention is illustrated in Fig. 7 of the drawings wherein a portion of a valve body, comparable to the valve body portion 45 shown in Fig. 6, is generally indicated at 53 and has an externally threaded portion 54y on which an internally threaded elastic flexible diaphragm cap member 55 is detachably threaded. The elastic flexible diaphragm cap member 55 is preferably made of a suitable synthetic thermoplastic resinous material, such as vinylidene chloride copolymer (Saran Dow Chemical Co.) and embodies a substantially flat and uniplanar elastic flexible diaphragm 56 which extends thereacross at one end of the valve body portion 53-54 and outwardly of a relatively thicker annular shoulder 51 formed thereon. This relatively thicker shoulder 51 prevents damage to or distortion of the elastic flexible diaphragm 56 during the operation of screwing the cap member 55 into position of use and removing it therefrom.

An additional modification of the elastic flexible diaphragm cap member of the present invention is illustrated in Fig. 8 of the drawings wherein a portion of a valve body is generally indicated at 58 and has an internally threaded portion 59 in which an externally threaded elastic flexible diaphragm cap member 60 is threadedly mounted. The internally threaded elastic flexible diaphragm cap member 60 is preferably made of a suitable synthetic resinous plastic, such as vinylidene chloride copolymer, and embodies a substantially annular Wall or shoulder 6| which is adapted to seat upon a substantially annular shoulder 62 formed upon the outer end portion 62 of the wall 59 of the portion 58 of the valve body. The elastic flexible diaphragm cap member 60 also embodies a substantially flat and uniplanar elastic flexible diaphragm 63 which extends across the outer end of the plug 60 inwardly of the substantially annular shoulder 6|.

A further modification of the elastic flexible diaphragm cap member of the present invention is illustrated in Fig. 9 of the drawings wherein a portion of a safety valve body is generally indicated at 64 and has an externally threaded neck 65 on which an internally threaded elastic flexible diaphragm cap member 66 is mounted. The elastic flexible diaphragm cap member 66 is preferably made of the same synthetic resinous plastic material as that preferably employed in making the elastic flexible diaphragm cap member 29 which is embodied in the form of the invention illustrated in Figs. 1 to 5, inclusive, of

nally threaded wall 65.

12 the drawings, although it may be made of other suitable synthetic resinous plastics or of Suitable metallic materials.

The elastic flexible diaphragm cap member 66 which is embodied in the modification of the invention illustrated in Fig. 9 embodies an inclined wall 68 having a beveled or inclined internal shoulder 69 which engages and seats upon a correspondingly formed inclined shoulder 10 which is formed on the upper end portion of the exter- The elastic flexible diaphragm cap member 66 also embodies a substantially flat and uniplanar elastic flexible diaphragm 61 which extends across and closes the outer end thereof inwardly of the substantially annular shoulder 68.

In the modification illustrated in Fig. 9, there are two seals, namely, a secondary seal between the internally threaded resinous plastic elastic flexible diaphragm cap member 66 and the safety valve body 64, and a primary seal between the two contacting beveled or inclined shoulders 69 and 10.

The modifications of the elastic flexible diaphragm cap members illustrated in Figs. '7, 8 and 9 of the drawings, and embodying substantially flat and uniplanar elastic flexible diaphragms 56, 63 and 61, possess considerably less flexibility than the corrugated elastic flexible diaphragms embodied in the forms of the invention shown in Figs. 1 to 5, inclusive, and Fig. 6 but possess sufiicient elasticity and flexibility to enable them to be used for many purposes.-

Another modification of the invention is illustrated in Figs. 10 and 11 of the drawings and this modification of the invention is especially adapted for use in those usages and instances in which a relatively high release pressure is desired in the use of the new safety valve.

In the modification illustrated ln Figs. 10 and 1l of the drawings a portion of a safety valve body is generally indicated at 1| and has an externally threaded neck 12, these parts 1|-12 corresponding to the internally threaded neck portion 3| of the valve body I I in the form of the new safety valve shown in Figs. 1 to 5, inclusive, of the drawings. The modification illustrated in Figs. 10 and 11 includes an internally threaded metal clamping ring 13 which is removably mounted upon the externally threaded wall 12 of the valve body portion 1I and this clamping ring 13 has an inwardly extending and substantially annular clamping flange or shoulder 14 formed integrally therewith at the outer end thereof.

The modification of the invention illustrated in Figs. 10 and 11 embodies an elastic flexible diaphragm 15 which is formed integrally with a substantially annular diaphragm ring 15 which is adapted to be seated on the outer end of the wall '|2 of the portion 1| of the safety valve body. The elastic flexible diaphragm 16 is preferably made of the same material as is employed in forming the elastic flexible diaphragm 34 which is embodied in the form of the invention illustrated in Figs. 1 to 5, inclusive, but differs therefrom, as may be seen by comparing Fig. 2 with Fig. 11, in that in the modification illustrated in Figs. 10 and 11 the elastic flexible diaphragm 16, and the annular clamping flange 15 which is formed integral therewith, are formed separate from rather than as integral parts of the members 12 or 13, on or in association with which they are mounted.

The elastic flexible diaphragm 16 embodies a Series of alternately arranged substantially annular concentric .corrugations provided by grooves 171 and .raised ribs "i8 which correspond structurally and Vfunctionally to the :alternately arranged substantially vannular corrugations provided "by 'the Ygrooves ,3'6 'and raised ribs 31 in the form of the invention illustrated in Figs. 1 to 5, inclnsive.

The -mddica'i'lion of the invention illustrated infFigs. il) Aand l1 embodies reinforcing and tensioning member inthe form of a 'relatively narrow Vband ror strip T9 of resilient spring steel or other' suitable 'metal ywhich vis attached to `the substantially annular shoulder M of the clamping ring 1-3 on-the yunderside of the said shoulder, thisattaohment being-effected by suitable vattaching elements, such as rivets 82, which are mounted on the substantially annular shoulder 14 4andwhich have their inner or rlower end portions 'attached to the resilient metal strip or band 19.

The resilient Ametal strip or band l .extends 4transversely and substantially diametrically across the substantially annular elastic vflexible diaphragm *l5 on the outer side thereof Yand has formed therein alternately arranged grooves or depressions 80 and raised ribs yil which match and :intert with and upon the grooves Tl and raised ribs 1-8, respectively, in the-elastic flexible diaphragm 1:5.

In :the Yuse of the modification shown rin Figs. v10 and l1 Vthe elastic flexible diaphragm 16 may be arrangednin position of use by 4mounting its supporting ring or clamping ange 15 on the outer endof the wall 12 of the portion 'Il of the safety valve body `and then screwing the threaded clamping ring 'I3 and attached resilient metal strip or ,band 79 carried thereby :into position of use upon Ithe neck -112v of the portion v'H `of the safety valve body until the :resilient ymetal strip or band 'i9 is disposed Yon contacting engagement with the elastic `flexible diaphragm 16 with the ggrooves 8d and the raised ribs 8l inthe resilient metal strip 79 interiitted lwith the corresponding grooves 1l 'and raised ribs 18, respectively, in the Velastic ilexible diaphragm 16. Wfhen so arranged the resilient metal :strip -or band 19 rreinforces land tensions the elastic flexible diaphragm 16 `and venables the modication of the invention illustrated in Figs. 10 and ll to be vused in those instances in vvv-hich a relatively high pressure valve release point lis desired and in which such pressure .valve release point is substantially higher than would be desired or necessary `in the use oi the unreinforced corrugated elastic hwxible diaphragm 34-36-37! which -isembodied -in the form 'of the invention illustrated 'in Figs. 1 :to 5, inclusive, to which the modincation illustrated in Figs. l0 and .ll -is otherwise -sinnlar both -structurally and functionally.

`While the resilient metal or spring steel band 1S isshown being a relatively narrow'strip, width and shape and yeffective surface area land thickness may -be varied, relative to the a-rea 'of the elastic lflexible diaphragm 'i5 over which it is arranged, so as to accommodate the elastic flexible diaphragm 16 :and the resilient or spring fsteel member T9 arranged thereover to any pressure release point which may -be desired in the safety valve in which these parts a-re embodied.

It will thus be seen from the foregoing dem vscription, considered in conjunction with the accompanying drawings, that the present invention provides a new and improved safety valve having the desirable characteristics and advantages hereinbefore referred to, vand others inherent Il h 14 therein, #and @that the present :invention thus iaccomplishes zits intended objects including 'those hereinbefore referred to and others which 'are inherent in the invention.

I claim:

1. .A safety valve Vcomprising fa valve'fh'ousing having Ian inlet and an outlet 'for gas or vapor under pressure, a rupturable Walliextending across the `said outlet, a valve seat disposed vabout the said inle't, valve means movably mounted in the said valve housing and v'including a movable valve member adapted to Vseat upon the said valve seat so as to :close the said inlet, and the said lsafety valve comprising a diaphragm cap member mounted upon the said valve housing and indluding an elastic ilexible diaphragm extending thereacross and normally 'bearing upon the said valve means to urge :the said Vmovable valve member 4into sealing engagement with the said valve seat so as to close the said inlet opening, the said diaphragm cap 'member including a substantially annular clamping Flange formed as an integral :part thereof and 'surrounding and of substantially tgreater t ickness than the said elastic iiexible diaphragm.

2. A vsafety valve as dened in claim l in which the said diaphragm cap vmember is `in lthe form oi a threaded member 'adapted 'to be detachably mounted upon a threaded portion of the said valve 'housing by threaded 'engagement therewith.

3. Asafiety valve as defined in claim 1 in `vvhi'c'h the said 'elastic flexible Ydiaphragm has a series 'of substantially annular and concentric cor-rugations :formed therein.

V4. A safety valve as defined in claim 1 in'which 'the said yelastic flexible diaphragm Vis formed .as a substantially flat and uniplanar wall.

5. A safety valve las defined in claim .l in Wh'ich fthe said movable valve .member has a 4tlfxreade'd valve :stem vattached thereto, and in which rthc lsaid 'threaded valve fste'm has a manually 'adinstable threaded member thereon, and inA which the said manually adjustable threaded member has aniend portion disposed in engagement with 'the surface lof the said exible diaphragm and is adjustable axially `relative 'to Vand along the said threaded valve stem, and in Which the :said safety valve :includes means fmounted upon the said threaded valve stem 'between the 'said movable valve member andthe said manually-ad- .'justable :threaded member and movable there'- with :and s'l'i'dably engageafble with the inner surface 'of :the said valve housing for vguiding -the movement 'of the 'said movable valve member yand its said `tlrrreaded valvestem and the said "manual- .ly :adjustable threaded l.member in and during 'movement thereof relative tothe said valve seat.

f6. .A .safety 'valve as defined in claim 1 in which the said movable valve member has Aa l threaded valve stem attached thereto, and in which the :said threaded valve stem has a man- :nal-ly adjustable member threaded thereon, and in which the vsaid manually adjustable threaded .inem-ber has an end vportion disposed in-engage'- nient with the A'inner surface of the said flexible .diaphragm and 'is adjustable axially along -the .said threaded Avalve stem, and in which the said valve housing yincludes a substantially ycylindrical portion, and in which the safety valve includes a substantially square member threaded 'onto the said threaded valve stem between the `said movable valve member and thesaidmanually `adjustable member 'and `slidably en'gage'able with the inner surface fof the said substantially cylin- `dr'ica-l portion of the said valve yhousing or lock;

ing the said manually adjustable member in a pre-selected adjusted position upon and relative to the said threaded valve stem and relative to the saidelastic flexible diaphragm and for guiding the movement of the said movable valve member and the said valve stem and the said manually adjustable member in the said valve housing and relative to the said valve seat.

7. A safety device as dened in claim 1 in which the said flexible diaphragm cap member is formed of a synthetic resinous plastic material and in which the said elastic flexible diaphragm is substantially annular in form and has a series of substantially annular concentric corrugations formed therein.

8. A safety valve as defined in claim l in which the said movable valve member has a threaded valve stem attached thereto, and in which the said threaded valve stem has a manually adjustable member threaded thereon which is adjustable axially along and relative to the said threaded valve stem, and in which the said flexible diaphragm is substantially annular in form and has a series of substantially annular concentric corrugations formed therein, and in which the inner surfaces of the said substantially annular corrugations are disposed in contacting engagement with the outer end portion of the said manually adjustable member.

9. A safety valve as defined in claim 1 in which the said valve housing includes a portion providing an internally threaded valve chamber and in which the said flexible diaphragm is formed as an integral part of an externally threaded diaphragm cap member removably threaded into the said internally threaded portion of the said valve housing.

l0. A safety valve as defined in claim 1 in whichl the said valve housing includes a portion -providing an internally threaded valve chamber and in which the said flexible diaphragm is substantially annular in form and is formed as an integral part of and as a Wall extending across the outer end portion of a substantially cylindrical diaphragm cap member which is removably threaded into the said internally threaded Valve chamber.

1l. A safety valve as defined in claim 1 in which the said movable valve member is substantially annular and cup-shaped in form and has a depending substantially annular skirt, and in which the said valve seat is substantially frusto-conical in shape and has a substantially annular groove formed therein upon its upper surface surrounding the said inlet and Within the confines of the said depending and substantially annular skirt of the said movable valve member when the said movable valve member is disposed upon the said valve seat,

12. A safety valve as defined in claim 1 in which the said valve housing includes an internally threaded outlet nipple having the said Valve outlet formed therein, and in which the said safety valve includes an externally threaded hollow safety plug removably threaded into the said internally threaded valve outlet nipple and having the said rupturable wall formed as an integral part of and extending across and closing the outer end of the said externally threaded hollow safety plug.

13. A safety valve as defined in claim 1 in which the said valve housing includes an externally threaded wall portion providing a substantially cylindrical valve chamber, and in which the said diaphragm cap member is substantially annular in form, and in which the said substantially annular clamping flange is adapted to rest upon the said Wall portion of the said substantially cylindrical valve chamber so that the said flexible diaphragm extends thereacross, and in which the said safety valve includes an externally threaded clamping ring adapted to be threaded onto the said externally threaded wall portion of the said substantially cylindrical valve chamber, and in which the said externally threaded clamping ring has a substantially annular inwardly extending clamping flange adapted to extend over and to clamp the said substantially annular clamping flange of the said diaphragm cap member in position upon the said externally threaded Wall portion of the said valve housing.

14. A safety valve as defined in claim 1 in which the said valve housing includes an externally lthreaded wall portion providing a substantially cylindrical valve chamber, and in which the said diaphragm cap member is substantially annular in form, and in which the said substantially annular clamping flange is adapted to rest upon the said Wall portion of the said substantially cylindrical valve chamber so that the said flexible diaphragm extends thereacross. and in which the said safety valve includes an externally threaded clamping ring adapted to be threaded onto the said externally threaded Wall portion of said substantially cylindrical valve chamber, and in which the said externally threaded clamping ring has a substantially annular inwardly extending clamping flange adapted to extend over and to clamp the said substantially annular clamping flange of the said diaphragm cap member in position upon 'the said externally threaded wall portion of the said valve housing, and in which the said flexible diaphragm has a series of substantially annular and concentric corrugations formed therein.

l5. A safety valve as defined in claim l in which the said valve housing includes a substantially cylindrical externally threaded portion, and in which the said diaphragh cap member is substantially annular in form and is internally threaded and is removably threaded onto the said substantially cylindrical externally threaded portion of the said valve housing with the said flexible diaphragm extending thereacross.

16. A safety valve as defined in claim 1 in which the said valve housing includes a substantially cylindrical externally threaded portion, and in which the said diaphragm cap member is substantially annular in form and is internally threaded and is removably threaded onto the said substantially cylindrical externally threaded portion of the said valve housing, and in which the said flexible diaphragm is formed as a substantially flat and uniplanar wall extending across the said valve housing.

1'7. A safety valve as defined in claim l in which the said valve housing includes a substantially cylindrical internally threaded portion, and in which the said diaphragm cap member is substantially annular in form and is externally threaded diaphragm cap removably threaded into the said internally threaded portion of the said valve housing with the said flexible diaphragm extending thereacross.

18. A safety valve as defined in claim 1 in which the said valve housing includes a substantially cylindrical internally threaded portion, and in which the said diaphragm cap member is substantially annular in form and is externally threaded and is removably threaded into the said substantially cylindrical internally threaded porl tion of the said valve "ascisse housing, and in which the said flexible diaphragm is formed as a substantially flat andvuniplanar wall of the said diaphragm cap member extending across the said substantially cylindrical portionof the saidyalve housing.

19. A safety valve as defined in claim 1 in which the said diaphragm capmember is substantially annular in formaand in which. the saidvalve housing includes a portion providing a substanf tially cylindrical valve chamber having an exterually threaded portion, andinwhich thesaid substantially annular diaphragm. can i member adapted to rest upon the wall of the said substantially cylindrical externally threaded portion of the said valve housing so that the said flexible diaphragm extends thereacross, and in which the said safety valve includes an internally threaded clamping ring adapted to be threaded onto the said substantially cylindrical externally threaded portion of the said Valve housing and having a substantially annular and inwardly extending clamping flange adapted to extend over and to clamp the said substantially annular diaphragm cap member in position upon the said wall of the said substantially cylindrical externally threaded portion of the said valve housing with the said flexible diaphragm forming an end wall extending thereacross, and in which the said safety valve includes a resilient reinforcing and tensioning member extending across the said flexible diaphragm on the outer side of and in contact with the said flexible diaphragm, and in which the said resilient reinforcing and tensioning member has its end portions retained in position by the said inwardly extending and substantially annular clamping flange on the said internally threaded clamping ring.

20. A safety valve as defined in claim 1 in which the said diaphragm cap member is substantially annular in form and in which the said valve housing includes a portion providing a substantially cylindrical valve chamber having an externally threaded portion, and in which the said substantially annular diaphragm cap member adapted to rest upon the wall of the said substantially cylindrical externally threaded portion of the said valve housing so that the said flexible diaphragm extends thereacross, and in which the said safety valve includes an internally threaded clamping ring adapted to be threaded onto the said substantially cylindrical externally threaded portion of the said valve housing and having a substantially annular and inwardly extending clamping flange adapted to extend over and to clamp the said substantially annular diaphragm Icap member in position upon the said Wall of the said substantially cylindrical externally threaded portion of the said valve housing with the said flexible diaphragm forming an end wall extending thereacross, and in which the said safety valve includes a resilient reinforcing and tensioning member extending across the said flexible diagram on the outer side of and in contact with the said flexible diaphragm, and in which the said resilient reenforcing and tensioning member has its end portions anchored to the inner surface of the said inwardly extending and substantially annular clamping flange on the said internally threaded clamping ring.

21. A safety valve as deiined in claim 1 in which the said diaphragm cap member is substantially annular in form and in which the said valve housing includes a portion providing a substantially cylindrical valve chamber having an 18 A externally threaded portion, A,anvil-in which the said substantially annular diaphragm capmember adapted to rest upon the wall of the said substantially cylindrical externally threaded portion of the said valve housing so that the said I iexible diaphragm extendsthereacross, and in which the said safety valve includes an internally threaded clamping ring adapted to be threaded onto the said substantially cylindrical externally threaded portion of the said valve housing and having a substantially annularv and inwardly' extending clamping flange adapted to extend over and to clamp the said substantially annularV diaphragm cap. member in positionyupon the said Wall of the said substantially cylindrical externally threaded portion of the said valve housing With the said flexible diaphragm forming an end wall extending thereacross, and in which the said safety valve includes a resilient reinforcing and tensioning member extending across the said flexible diaphragm on the outer side of and in contact with the said flexible diaphragm, and in which the said resilient reinforcing and tensioning member has its end portions retained in position by the said inwardly extending and substantially annular clamping flange on the said internally threaded clamping ring. and in which the said flexible diaphragm has a series of substantially annular concentric corrugations formed therein, and in which the said resilient reinforcing and tensioning member has a series of correspondingly shaped substantially annular concentric corrugations formed therein complementary to and interfitting with the said substantially annular concentric corrugations in the said flexible diaphragm.

22. A safety valve as defined in claim 1 in which the said diaphragm cap member is substantially annular in form and in which the said valve housing includes a portion providing a substantially cylindrical valve chamber having an externally threaded portion, and in which the said substantially annular diaphragm cap member adapted to rest upon the wall of the said substantially cylindrical externally threaded portion of the said valve housing so that the said flexible diaphragm extends thereacross, and in which the said safety valve includes an internally threaded clamping ring adapted to be threaded onto the said substantially cylindrical externally threaded portion of the said valve housing and having a substantially annular and inwardly extending clamping flange adapted to extend over and to clamp the said substantially annular diaphragm cap member in position upon the said wall of the said substantially cylindrical externally threaded portion of the said valve housing with the said flexible diaphragm forming an end wall extending thereacross, and in which the said safety valve includes a resilient reinforcing and tensioning member extending across the said flexible diaphragm on the outer side of' and in contact with the said flexible diaphragm, and in which the said resilient reinforcing and tension ing member has its end portions retained in position by the said inwardly extending and substantially annular clamping flange on the said internally threaded clamping ring, and in which the said resilient reinforcing and tensioning member consists of a band of resilient spring steel extending substantially diametrically across the said flexible diaphragm and having its end portions anchoredV to the inner surface of the said inwardly extending and substantially annular Muller Oct. 25, 1982 Name Date Deming v -..1 Dec. 18, 1934 Smith July 14, 1936 Work Aug. 12, 1941 Kaelin June 15, 1943 yFOREIGN PATENTS Country Date Australia Aug. 9, 1928 OTHER REFERENCES Goggin: Vinylidene Chloride Polymers, Industrial and Engineering Chemistry, March 1942. 

